To develop alternative methods for the testing of chemicals for toxicity, mutagenicity, and/or carcinogenicity in order to increase test sensitivity, decrease time requirements, and reduce the number of animals required for chemical safety evaluation. The selection, development, and evaluation of transgenic mouse model systems has the following three main goals: (1) screen large numbers of chemicals (mutagens and non-mutagens) in a rapid and efficient manner, (2) analyze and compare mutagenic (and non-mutagenic events affecting cell function) and carcinogenic events at the chromosomal and/or molecular level within the same protocol, and (3) develop cultured transgenic cell lines from normal tissues and spontaneous and chemically induced site specific tumors for detailed analysis.